Field of the Invention
Embodiments of the present invention relates to the art of a vehicle control system configured to switch an operating mode of a vehicle between manual mode and autonomous mode.
Discussion of the Related Art
U.S. Pat. No. 6,253,137 describes an oil pressure supply device for vehicle drive system configured to improve the efficiency of the energy used to drive the oil pump. The hybrid vehicle taught by U.S. Pat. No. 6,253,137 is provided with a V-belt continuously variable transmission for transmitting power of a prime mover to drive wheels, and an electric oil pump for delivering oil to the transmission and to lubrication sites. According to the teachings of U.S. Pat. No. 6,253,137, the microprocessor is programmed to reduce a discharging amount of the oil pump when the transmission is not varying the drive ratio, and to increase a discharging amount of the oil pump when the transmission is varying the drive ratio.
JP-A-2012-59274 describes an automatic drive vehicle that can be operated automatically according to a preset travel plan. According to the teachings of JP-A-2012-59274, specifically, the vehicle is operated automatically by controlling a vehicle speed and steering angle in such a manner to achieve a target pattern of the vehicle speed and a target travel locus.
As described, according to the teachings of U.S. Pat. No. 6,253,137, a discharging amount of the oil pump is increased when the transmission is varying the drive ratio to ensure an oil pressure and an oil delivery amount required to carry out a speed change operation and lubrication. However, the automatic transmission used in automobiles may require a larger amount of oil in situations other than during a speed change operation, for example, when generating a large driving or braking force. For this reason, in the conventional automobiles, the oil is delivered to the oil requiring site in an amount larger than the required amount even under a steady running condition. Consequently, the oil may be applied excessively to the transmission and rotary members and hence energy may be wasted by an agitation loss. In addition, oil pressure may also be raised more than required. In the conventional automobiles, therefore, energy efficiency such as fuel efficiency and electric efficiency may be down.
By contrast, in the automatic drive vehicle taught by JP-A-2012-59274, a required amount of the oil will not be increased by an operation of a driver. For this reason, an agitation loss may be reduced by suppressing an oil delivery amount, and an energy loss resulting from driving a hydraulic source may also be reduced by lowering an oil pressure generated by the hydraulic source. However, such energy loss has not yet been explored sufficiently so far in the prior art. Therefore, energy efficiency of the conventional autonomous drive vehicle has to be improved by reducing a pressure and an amount of the oil delivered to the oil requiring site.